Manufacture of antiknock motor fuels



July 13, 1943- A. R. GQLDsBY ET Al.` J 2,324,295

MANUFACTURE OF ANTIKNOCK MOTOR FUELS Filed DeC. 28, 1939 WL! s /dw TH /RAT RNEYS Patented July 13, 1943 2,324,295 MANUFACTURE F ANT'IKNOCK MOTORFUELS Arthur B. Goldsby and Eugene E. Sensei, Beacon, N. Y., assignors,by mesne assignments, to The Texas Company, New

of Delaware York, N. Y., a corporation Application December 2s, 1939,serial No. 311,304

11 claims.

This invention relates to the manufacture of antlknock motor fuels andhas to do particularly with the treatment of petroleum naphthas toimprove the antiknock property.

It is known that naphthas or gasolines, consisting mainly of straightchain paraffin hydrocarbons of relatively low antiknock value, may besubstantially improved in antiknock value by treatment with anisomerization catalyst, whereby the straight chain paraiiln hydrocarbonsare converted into branch chain orisoparaiiin hydrocarbons of highantiknock value.

It has been found that certain naphthas, particularly those of highboiling range, or wide boiling range naphthas containing higher boilingfractions, on isomerization with catalysts, such as metallic halides,may give relatively poor results due to low octane improvement and highcatalyst loss or consumption. Thishas been found particularly true ofthose naphthas containing substantial amounts of aromatic and/orunsaturated hydrocarbons. 'I'he aromatic and unsaturated hydrocarbonsgenerally have a high The net advantage, therefore, of the isomerizatonof such naphthas to convert normal parafns to isoparafns may be largelyoifset by the loss of the unsaturated and aromatic content.

In accordance with the present invention, naphthas, normally containingconstituents which cause deterioration of the catalyst, are treatedunder extracting conditions with a solvent selective-for the removall ofthe lconstituents lwhich cause deterioration of the catalyst. Thereiined naphtha, after separation of the solvent and extract, can betreated with the isomerization catalyst. whereby the antiknock propertyof the treated naphtha may be substantially improved, with increasedeffectiveness and' yield per unit weight of catalyst. The aromatic andunsaturated hydrocarbons which are re moved in the extract can berecovered for use. in blending with the isomerized product or othermotor fuel base stock.

Naphthas which may be treated are of wide. variety. It is intended totreat any naphthas or gasolines, or fractions thereof, which contain asubstantial proportion of low octane paraifn-hydrocarbons, as well asconstituents which cause objectionable deterioration oi the catalyst.

Naphthas specicallyintended are straight run naphthas, containingaromatics and/or unsaturated compounds; cracked naphthas; mixtures ofstraight run and cracked naphthas; and naphthas resulting from catalyticcyclization of olens.

'I'he naphthas or-gasolines to be treated with the isomerizationcatalyst may be separated into two or more fractions and one or more ofthe fractions treated and the products blended. Thus a naphtha may beseparated intoA low boiling and high boiling fractions and each fractiontreated separately, or only one fraction, such as the high boilingfraction, treated. The fractions may then be recombined.4

For example, a straight run naphtha mayy desirably be separated into twofractions. One may be a low boiling fraction having an end point belowthe boiling point of the lowest boiling aromatic constituents in thestock in question, such as below about 200 F. The other may be a higherboiling fraction containing substantially all the aromatic content ofthat stock. The low boiling fraction is isomerized or may be leftuntreated, depending upon the octane thereof and the octane of the nalproduct desired. The higher boiling fraction is solvent reiined "and the'resulting ramnate thereafter amountv of aromatics, but even a smallamount is harmful to the isomerization reaction. A

cracked naphtha fraction, however, of such boling range containsunsaturated or oleflnic hy drocarbons which are advantageously removed.

Furthermore, a fraction of safety fuel boiling range, for example, aproduct with a flash above F., and a boiling range of about 300 to 500F. may be treated, if desired. 'I'he preliminary, removal of aromaticsand unsaturates enablesl the treated product to be successfullyisomerized.

to improve the antiknock characteristics..

In case the proportion of aromatics or unsaturates in the oil is low, asin the case of some straight run paramnic naphthas, it may be de.-sirable to treat the naphtha with acid or alumlnum chloride to removethe small amount of washing with water.

aromaticsor unsaturates and then isomerize the treated product, ratherthan to isomerize the naphtha directly, or to solvent refine and thenisomerize.4

'I'he preliminary solvent rening or extraction step may be carried outby conventional processes and with any solvent suitable for thispurpose. The solvent extraction of light oils is quite well known in theart, and itis intended that any of these methods may be used. Speciilcsolvents which may be mentioned are sulfur dioxide or mixtures ofsulfurdioxide with methyl alcohol, benzyl alcohol or diacetone alcohol. The

sulfur dioxide extraction is ordinarily carried out in the liquid phaseat temperatures of about to 60 F. In carrying out the extractionprocess, the solvent is contacted with the oil under temperature andpressure conditions to cause an extraction of certain constituents suchas unsaturates and oleiins, thereby forming an extract and raillnatelayer, and then separating the two layers. Any solvent retained in thetwo layers may be removed, for example, by distillation or 'I'he ramnatelayer will contain straight chain or paramn hydrocarbons of lowantiknock value suitable for treatment by isomerization. Ihe extractlayer after separation of the solvent will usually contain high santiknock hydrocarbons which maybe used for motor fuel, for example, byreblending with the isomerized ramnate.

'I'he preliminary treatment with reagents, such as aluminum halides orsulfuric acid, produces' chieiLv polymerization products of thelunsaturates, or complexes or sludge with the unsaturates or aromatica,which may be separated from the treated oil as sludges. The treatmentmay. be conducted at low temperatures within the range specified forsolvent refining or at somewhat higher temperatures. Such treatment maybe economical with naphtha containing relatively small amounts ofunsaturafes or aromatics or both. The treating agent is usuallycontacted with the oil in the conventional manner of acid treating.

I'he isomerization of straight chain paramn tion, a straight rungasoline of 100 to 390 I".

operations. In continuous or. cyclic operations,

for example wherein the oil is contacted with the catalyst in la packedtower,.the proportion of catalyst to oil undergoing treatment at anygiven interval of time may be considerably larger than in the case ofbatch operations, but the ultimate yield of total hydrocarbon treatedper unit of catalyst may be considerably larger in the continuous typeofl operation.

As an example of the operation of the invening an antiknock value ofabout 40, are obtained. v

The ramnate is treated with about 15% aluminum chloride and 0.8%hydrogen chloride. The yieldvof treated naphtha is about 95% and theantiknock value thereof is about 65. When the extracted hydrocarbons arereadded to the treated naphtha, a blend having an octane number of about'71 may be obtained. The same naphtha, without the preliminaryextraction step, could not be successfully treated with the Catalysis,which have been propod for that purpo, include anhydrous metallichalides, particularly thechlorides. bromides, etc., of aluminum,zirconium. iron, zinc, tin, barium, columbium, tantalum and boron,together with small amounts of hydrogen halides, such as hydrogenchloride, as promoters. We prefer to use aluminum chloride and hydrogenchloride. 'Ihe reaction may be carried out in the liquid or vapor phase'by contacting the oil with the catalyst, alone or supported on asuitable carrier, such as clay, pumice, brick, coke, activated `aluminaor carbon. It is preferable to carry out the reaction under temperatureand pressure conditions such as to maintain the liquid phase. Thedeterioration of the catalyst may be retarded by carrying out theprocess in the presence of substantial amounts of low boilingisoparafiins, such as isobutane or isopentane. The temperatures arepreferably in the range of about 180 1". to 270 F. although temperaturesup to 360 l". or

` higher may be used.

conducted from `a source not shown through a.

pipe I is subjected to fractionation ina fractionation unit-2. toproduce a fraction boiling in the range of around 1D0-200 P'. Thisfraction is and conducted to a receiver I.

From the receiver I the low boiling material may be passed to anisomerisation unit l wherein it is subjected to isomeriaation. Theisomerized hydrocarbons are drawn of! through a pipe 5 and, all or inpart, conducted to a tank 0.

The higher boiling fraction formed in the fractionation unit 2 is drawn'of! through a pipe 'i to an extraction unit 8. In this extraction unitthe naphtha hydrocarbons are treated so'as to extract from themunsaturated and aromatic hydrocarbons.l 'I'his extraction may beeffected by treatment with acid or aluminum chloride or by treatmentwith a selective solvent such as sulfur dioxide.

The vunsaturatedv and aromatichydrocarbons so extracted from the naphthaare separated fromtheextractingmediumandpassedtoa tank 9 from which theymay be passed, all or in part, to the previously mentioned tank l.

The naphtha hydrocarbons from which the unsaturated and aromaticconstituents have been removed are to a tank Il and from there theyaresubiected to contact with an isomeriza- Insuchcaseths between about0.1 and 5% or more. nfmbly den of ting a low boiling fraction-for about1%. Thehtterilguresarebasedonbatth 75 @Pirate treatment is omitted.

The fractionation is such as The process of the present invention,wherein the oil is treated to remove aromatics and unsaturates, prior toisomerizatlon, produces a yield of about 80 to 95% of product showing anoctane improvement of about to 40 points. Similar isomerizationtreatments, without the preliminary solvent extraction treatment,produce yields o'i about 50 to 80% with very little improvementobtained. In fact, some times a loss in octane may occur, due to removaloi unsaturates and aromatics. Moreover, the catalyst deterioration isusually substantially less in treating' gasolines which have,beensubjected to the preliminary solvent extraction step.

Obviously many modications and variations of the invention, ashereinbefore set forth, may be made without departing from the spirityand scope thereof. and therefore only such limitations should be imposedas are indicated in the appended claims.

We claim:

1. A process involving catalytic isomerization, for improving theantiknocl-r properties of naphtha of relatively low antiknock value andnormally containing constituents of the class of unsaturates andaromatics which cause deterioration of the catalyst, which comprisesseparating the naphtha into a low boiling fraction having an end pointbelow the boiling range of at least the major portion of the aromaticsin the stock and a high boiling fraction, solvent refining the highboiling fraction to remove coning treatment with an isomerizatloncatalyst.

' which comprises separating the naphtha yinto a low boiling fractionhaving an end point-,below the booling range of at least the majorportion of the aromatics in the stock and a high boiling fraction,separating from the high boiling fraction a fraction' rich in aromatichydrocarbons and comprising constituents highly reactive toward thecatalyst and capable of causing substantial catalyst deterioration,subjecting the high boiling naphtha hydrocarbons from which saidaromatic-rich fraction has been removed to contact with an isomerizationcatalyst under conditions such that isomerization of non-aromaticconstituents constitutes the principal reaction and said reaction iseiected with substantial decrease in catalyst deterioration, andblending resulting isomerized hydrocarbons with at least a portion ofthe low'boiling fraction.

6. A process for improving the antiknock properties of naphtha ofrelatively low antiknock value and containing unsaturated constituents,aromatic hydrocarbons and non-aromatic hydrocarbons including paraflins,involving treatment .with an isomerizatlon catalyst, which comprisesfractionating the naphtha into a low boiling stituents which causedeterioration of an aluminum chloride isomerization catalyst, subjectingthe treated high boiling .fraction under isomerizing conditions withsaid isomerization catalyst and blending the isomerized high boilingfraction with the low boiling fraction.

2. A process according to claim 1 in which the original naphtha is astraight run product and the low boiling fraction is isomerized prior toblending with the high boiling fraction.

3. A process according to claim 1 in which the original naphtha is acracked product and the low boiling fraction is treated to removeunsaturated products therefrom and then isomerized prior to blendingwith the high boiling fraction.

4. A process. involving catalytic isomerization. i'or improving theantiknock properties of naphtha of relatively low antilmock value andnormally containing constituents of the class of unsaturates andaromatics which are capable of causing deterioration of the catalyst,which comprises separating the naphtha into a low boilfraction having anend point below the boiling range of at least the major portion of thearomatics in the stock and a high boiling fraction, separating from saidhigh boiling fraction a fraction rich in aromatichydrocarbons andcomprising constituents highly reactive toward the catalyst and capableof causing substantial catalyst deterioration, subjecting the llowboiling tion is eil'ected with substantial decrease in cataing fractionhaving an end point below the -boil- A halide isomerization catalystunder conditions such that there is substantial isomerization oi naphthahydrocarbons, and blending at least in part isomerized high boilingfraction with the low boiling fraction.

5. A process for improving the antiknock properties of naphtha ofrelatively low antiknock .value and containing unsaturated constituents,aromatic hydrocarbons and non-aromatic hydrocarbons including :pai-amas.involvunsaturates and lyst deterioration. and blending resultingisomerized hydrocarbons with aromatic hydrocarbons separated from saidhigh boiling fraction.

7. A process, involving catalytic isomerization, for improving theantiknock properties of naphtha of relatively low antiknock value andnormally containing constituents of the class of aromatics which causedeterioration of the catalyst, which comprises separating the naphthainto a low boiling fraction having an end point below the boiling rangeof at least the major portion of the aromatics in the stock and a highboiling fraction, chemically treating the high boiling fraction toremove con- Y stituents which cause deterioration of an aluminumchloride isomerization catalyst, subjecting the treated high boilingfraction under isomerizing conditions with said isomerlzation catalystand blending resulting isomerized hydrocarbons with at least a portionof the low boiling fraction.

8. 'I'he process according to claim -4 in which the original naphtha isobtained by catalytic conversion of hydrocarbons and the low boilingfraction is treated to. remove unsaturated products therefrom and thenisomerized prior to blending with the high boiling fraction;

9. 'Ihe process according to claim 4 in which the original naphtha isobtained by cracking hydrocarbons and the low kboiling fraction istreated to remove unsaturated products therefrom and then isomerizedprior to blending with the high boiling fraction.

10. The process accordingto claim 5 in which isomerized hydrocarbons,the lowV boiling fraction and aromatic hydrocarbons separated from thecausing deterioration of the catalyst, which 10 comprises separating thenaphtha into a low boiling fraction having an end point below theboiling range of at least the major portion of the aromatics in thestock and a high boiling fraction, separating from the high boilingfraction constituents which are capable of causing deterioration of anactive metallic halide isomerization catalyst, subjecting the lowboiling fraction and said high boiling fraction from which saidconstituents have been separated to contact with an active metallichalide isomerization catalyst under conditions such that there issubstantial isomerization of naphtha hydrocarbons and forming a blendcomprising isomerized hydrocarbons from both said fractions.

ARTHUR R GoLDsBY. EUGENE E. sENsEn

